The additional drag, which arises from laminar separation bubbles, can be eliminated, by avoiding them or by reducing their size, using one of the following measures:
- natural transition by shaping the airfoil geometry in such a way that the transition occurs already in front of the main pressure recovery region, where the bubble might occur, or by
- forced transition by artificial disturbances, e.g. a turbulator. This device will usually be attached just before the region of laminar separation and has to introduce enough disturbances to cause transition into the turbulent state, before the laminar separation can occur.
For the low Reynolds numbers of model aircraft, forced transition by means of a turbulator seems to be more recommendable. A small drag increase in the high speed regime is the cost which has to be paid for the bigger improvements at low flight speed. It is not a result of a bad design, when an airfoil needs a turbulator for best performance - at least not at Reynolds numbers below 1 million.
The turbulator causes transition without laminar separation.
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